Fast well. Eat well.
Know what your body's doing.
Prosper is a quiet metabolic coach — a fasting timer with real safety rails, glucose insight without the noise, and an AI coach that knows your last month, not just your last message.
Closed beta
Ask about the betaA fasting app you don't have to argue with
Start, end, edit, or back-log a fast — your record stays yours to correct. Zones for fat-burning and ketosis are shown as the typical guides they are, never as measurements.
Fasts heading past 24 hours get a genuine contraindication screen — pregnancy, diabetes medication, eating-disorder history — not a cheer squad. The app would rather you stop than streak.
Optional, silent notifications at the fat-burning and ketosis marks and at your goal. Off by default. No badges, no confetti, no guilt.
Log readings or sync a sensor. See your day's curve honestly — measured points marked at their true time, modelled estimates clearly labelled as modelled.
Ask anything. The coach knows your goals, your fasts, and your patterns — but only ever what you've explicitly agreed to share, and it never leaves without consent.
Shift roster aware. Water in glasses, not ounces-toward-a-goal. Protein-first food logging that doesn't count a single calorie at you.
The honesty rule. Every number in Prosper says where it came from — measured, modelled, or logged by you. If the app estimated something, it tells you. If it doesn't know, it says nothing rather than making it up.
Your data lives on your phone
Prosper keeps your health record in a local database on your device. There are no analytics, no ad trackers, and no account to create. The only thing that ever leaves your phone is a coach conversation — and only after you've read exactly what travels with it and switched it on yourself.
The full detail, in plain language: the privacy policy.
Built in New Zealand
Made by Silver Fern Labs in Aotearoa New Zealand — home of clean air, long coastlines, and the occasional very good walk. Designed for everyone, everywhere.